Beating the Heat without AC

It’s been a summer to savor—with an abundance of sunny days, dry air and invigorating breezes. The searing heat waves afflicting other parts of the country and globe can seem like shimmers of a distant mirage.

When we use air conditioning to cope with heat, we exacerbate the problem. Mechanized cooling systems drive more greenhouse gases into the atmosphere, further aggravating global warming. What scientists term a “positive feedback loop,” most of us would simply call a “vicious cycle.”

That cycle is gaining momentum worldwide as more and more people in fast-growing nations like India and China acquire and use air conditioners. The power consumption of computer data centers, which demand round-the-clock cooling, quadrupled from 2007 to 2013. Within the next three decades, the energy used worldwide in cooling could overtake that used in heating.

Nearly 90 percent of U.S. buildings now have air conditioning, sending electricity use soaring during warm months. Stan Cox, author of “Losing Our Cool: Uncomfortable Truths about Our Air-Conditioned World,” observed in 2010 that the United States uses as much electricity for air conditioning as the 930 million residents of Africa consume for all purposes. Our nation’s air conditioning generates about 100 million tons of carbon dioxide annually, and costs consumers upwards of $11 billion a year.

One other major drawback to air conditioning receives little press. Many people recall the unnerving realization that chlorofluorocarbons (CFCs) used in aerosols and refrigerants were eroding Earth’s stratospheric ozone layer. That crisis led to signing of the Montreal Protocol on Substances that Deplete the Ozone Layer in the late 1980s, a successful international treaty that has helped the ozone layer recover.

But as often happens, the “new and improved” substitute now used widely in air-conditioning systems – hydrofluorocarbons – generates a different concern. While not depleting ozone, HFCs trap atmospheric heat up to 10,000 times more effectively than CO2. Further international action by amending the Montreal Protocol is needed now to limit release of HFCs.

While air conditioning can be a lifesaver during three-digit heat waves, most warm spells in New England can be tolerated without 24/7 air conditioning. If we design and manage buildings for passive cooling and adopt some creative coping strategies, we can beat the heat without further pummeling the planet.

COOL DESIGN

Everyone knows that sound insulation makes a building more comfortable and efficient in winter, but fewer people recognize how beneficial insulation can be in the dog days of summer. Added insulation helps on the hottest days – particularly if occupants open windows wide at night and close them in the day to trap cooler air inside.

Solar shading can greatly reduce the radiant heat absorbed through windows (particularly on south and west sides), and architecture in tropical regions often accommodates this through overhangs, porches, shutters and awnings.

Fewer houses in Maine have these features so we’re left to improvise. My family’s home has a south-facing overhang that shelters some windows, but for others we’ve devised an implausible but effective system involving bubble wrap. On the hottest days, we slide sheets of “double reflective insulation” – which we custom-cut from a long roll – between the window glass and screen, helping to reflect radiant energy. This technique, combined with nightly opening of windows, keeps the house 5 to 10 degrees F cooler.

Solar shading works even if you’re a renter (as long as windows can be opened; avoid hermetically sealed units). And homeowners can opt for a long-term strategy with a far nicer aesthetic – planting shade trees on the south and west sides of the house. Even before they begin the work of shading, these trees will be doing their part to absorb greenhouse gases.

DON’T GENERATE HEAT INDOORS

You can’t squelch the heat generated by your refrigerator during hot weather, but you can give your clothes dryer a sabbatical. Hang laundry outside and you’ll save on expenses, get free solar bleaching services and keep the indoor temperature cooler. Think twice, as well, about baking and stove-top use during hot spells. If you haven’t already switched to LED lightbulbs, they generate far less heat than incandescents – and save on electricity over the long haul.

DRESS FOR THE WEATHER

Many professional offices are overcooled, with air conditioning set to keep those in business suits comfortable. The solution couldn’t be simpler: Have employees dress for the weather – permitting short-sleeved shirts and tailored shorts on the hottest days of the year. Tell your clients or customers that this is a variant of “Casual for a Cause” – only this cause is keeping a livable planet.